There's also a fellow north of Atlanta that advertises on Craigslist, haven't actually dealt with him but did speak over the phone and he always has something coming and going, and seems willing to haggle.

Single rear wheel Type A's are pretty rare in my experience and don't even have the width of a dually Type A. They're also already at their GVWR just sitting empty before any conversion weight is added.

As for your years preference I wouldn't buy anything newer than 2007 (if diesel).